Research On Fixed Integer Ambiguity Algorithm With Linear Constraints

With the development of GNSS technology,higher requirements have been set for highprecision positioning,navigation,and timing in many areas.At the same time,China's BDS system is also rapidly developing and researching.In this context,the key to high-precision positioning is the cycle slip detection and repair in the data preprocessing stage and the whole cycle ambiguity resolution.Accordingly,the cycle slip processing effect of carrier phase observations and the accuracy of the ambiguity resolution Both will determine the accuracy of the positioning results.This paper studies representative cycle slip detection and repair and ambiguity resolution methods,and applies them to the carrier phase observations of three BDS satellites,and obtains some useful conclusions.For the widely used ambiguity solution method LAMBDA algorithm,carry out in-depth research,try to improve from the prior linear constraint conditions,the accurate calculation of intermediate process quantities,and the selection strategy of the reference satellite,and finally conclude that the algorithm is feasible Sex.The work done in this article mainly includes the following aspects:(1)The basic development of GNSS and the current problems are described.The research background of cycle slip detection and repair in GNSS data preprocessing and the determination of the whole week's ambiguity are introduced.(2)Based on the basic GPS observation model,the common observation model is thoroughly researched and derived,and the single-difference and double-difference models and their combined virtual observations in relative positioning are analyzed.The requirements of the combined virtual observations and the basic combination form are analyzed,and then the error terms of the basic observations and the reasons for the errors are explained in detail.Aiming at the mixed observation ephemeris released by MGEX,this article explains its basic observation structure and observation type.(3)From the perspective of the carrier phase observations' change law and combination form,the common model polynomial fitting method and high-order difference method are deduced and summarized,and they are applied to the carrier processing of three BDS satellites,and some useful results are obtained.Conclusion;The ionospheric residual method is deduced and applied to three BDS satellites,and it has obtained good calculation accuracy.In this paper,based on the combination of basic observations,a recursive formula is proposed to improve the combination of dual-frequency codes.The richer types of wide lane combinations have achieved better results when applied to BDS satellites.(4)In view of the characteristics of the ambiguity in the carrier phase observations,this paper starts with the calculation of the approximate ambiguity of the smooth pseudorange,and gradually proceeds to use the basic observations to combine to obtain the combined ambiguity.Research and application of super wide lane ambiguity.Based on the ambiguity of the dualfrequency code,a ambiguity-independent ambiguity algorithm is derived in this paper,and it is applied to BDS satellites with good results.(5)Aiming at the commonly used ambiguity solution method LAMBDA algorithm,this paper attempts to improve it by using high-precision prior linear constraints.According to the characteristics of the LAMBDA algorithm,this paper divides it into three calculation processes,and improves each calculation process separately.First of all,the satellite ephemeris interpolation method is improved.A new sliding Lagrange interpolation algorithm is proposed in this paper,which effectively avoids the endpoint Runge phenomenon,and the interpolation accuracy of the instantaneous space coordinates of GPS satellites and BDS satellites can reach millimeters.Level,which effectively improves the interpolation results;secondly,the calculation method of satellite altitude angle is derived from the selection of aerial satellites corresponding to the observations of the two stations,taking into account the size of the satellite altitude angle and the effective data amount of the measured data,improving the reference observation station and The selection strategy of the reference satellites better combines the station-dual double-difference model;based on the linear condition of the a priori constraint,when the data is collected in the field,the baseline measurement accuracy is deliberately improved.Through calculation and analysis of the measured data,conclusions are obtained that are conducive to the resolution and fixation of ambiguity.